This invention relates generally to the art of producing charcoal, and secondarily fuel gas, from organic material, and more particularly concerns an apparatus and method in such art which is self-sustaining in operation.
The use, per se, of a pyrolysis process to convert organic material, such as wood chips, to charcoal and fuel gas is well known, and a wide variety of devices have been designed to accomplish such a result. A primary disadvantage of such devices, including those generally referred to as gasifiers, is that a substantial produced charcoal is substantially consumed. A recognized by-product of the pyrolysis process is tar, which affects both the operation of a gasifier and the end use apparatus of the produced fuel gas, such as an internal combustion engine or other burner. The production of tar is discussed in U.S. Pat. No. 4,268,275 and U.S. Pat. No. 4,421,524 both to Chittick and U.S. Pat. No. 4,530,702 to Fetters et al. The solution regarding tar, disclosed in these patents, included a reaction chamber having a pyrolysis zone followed by a reaction zone comprising a bed of charcoal heated to a high temperature. The high temperature of the charcoal and the catalytic effect of the ash residue on the surface of the hot charcoal break down the tars from the pyrolysis zone into carbon monoxide and hydrogen. The heat for the pyrolysis zone and the reaction zone was provided externally. The issue of minimizing the consumption of charcoal is not addressed. U.S. Pat. No. 4,530,702 to Fetters et al additionally disclose the introduction of steam for increased fuel gas production. The introduction of steam is counterproductive vis-a-vis the production of charcoal increasing the production of carbon fines and production of ash, both having little or no value.
Also noted herein are U.S. Patents to Brioni et al, U.S. Pat. No. 5,725,738; to Koslow, U.S. Pat. Nos. 5,946,342 and 6,061,384; and Nagle et al, U.S. Pat. Nos. 6,051,096 and 6,124,028.
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